Masking strip



Sept 5,. 1939. J. c. DoTY E'r AL l 2,171,544

- MSKING STRIP l Filed Sept. 14, 1932 Patented Sept. 5, 1939 UNITED STATES PATENT OFFICE MASKING STRIP tion of Delaware Application September 14, 1932, Serial No. 633,187

4 Claims.

Reference is made to our Patent No. 1,779,588,

'granted October 28, 1930, wherein is described lo the subject matter of lthis application,`and in 2 which the claims are directed to the masking strip.

.The present practice of application of various colors to automobile bodies, especially by means of asprayvgun, requires the protection of various portions of the body, at different times, from the spray, the application of which cannot be accurately controlled by the spray gun itself. For this purpose it has been customary, recently, to use an adhesive tape,xquite like the well-known surgical adhesive tape. The common practice, especially where the work is being performed by a single workman, is tocause the tape to adhere, by light pressure along a line inmediately adjacent the surface which is to be coated. The very edge of this tape is then lifted slightly and a sheet of paper of desired extent inserted beneath it and the tape then pressed to place. 'Ihe sheet of paper will have sufficient width and extent to thoroughly protect the surface which is to be protected and when the application of color has been completed the tape is stripped from the surface and thrown away because the adhesive material carried by the tape is of such character that having been once applied to any surface, it does not again firmly adhere to another surface. Occasionally a second use of the tape may be had, but not often. The application of proper masks to a job, such as an automobile body, by the above described means and method is a Atedious and time consuming operation and is also fairly expensive because of the limited usability of the adhesive tape.

The object of our present invention is to provide a masking strip of such character that it may be readily and quickly applied to surfaces to be masked and such that it may be repeatedly used upon successive jobs.

The accompanying drawing illustrates our invention, I indicating a sheet or strip of paper or other suitable flexible and protective material, of convenient width, say about 9 more or less, and carrying upon one edge a comparatively narrow strip Il of an adhesive material prefer- 55 ably of such character that it may be firmly associated with the paper strip and, when applied with light pressure and at normal temperatures, will adhere firmly against a lateral displacement in the plane of the sheet,lto many successive surfaces to which it may be applied, yet may be readily stripped from such surfaces.

While there may be many compositions of matter which will possess the desired adhesive qualities and which will retain such qualities for extended periods of time and through many suc- 10 cessive applications to surfaces to be protected, our present knowledgeA has led us to the belief that the most satisfactory results may be obtained in the following manner:

Assuming that approximately 100 lbs. of ad- 15 hesive material is desired, we take 60.25 lbs. of commercial rubber hydrocarbon to which We add sufficient benzole, say about 5 lbs., to produce a liquid of about the `consistency of whipping cream. To this we add 15.46 lbs. of zinc oxide stirring thoroughly until a doughy mass has been produced. We then add, without regard to order of addition, 8.95 lbs. of organic acetone, 1.11 lbs. chloroform, 8.20 lbs. sulphur and 1.03 lbs. paraffine oil, stirring the mass until it is thoroughly mixed and forms a dough-like mass which is then rolled between polished rollers to a desired width and thickness, say from 1/2 to 1" Wide and about 0.003l in thickness and applied to a strip of Holland or other protective material which will strip readily therefrom. The exposed surface of the adhesive is then slightly moistened with benzole andthe exposed surface is then applied, with considerable pressure to the desired portion of the paper strip I0.

The application of the adhesive to the paper in the above described manner causes such an intimate contact between the paper and the adhesive that the adhesive cannot be readily separated from the paper. If desired the Holland may then be stripped from the adhesive and the sheet rolled into convenient form for shipping and handling.. Care must be exercised not to bring two portions of the exposed face of the adhesive together, because, when that is done, separation tears the adhesive and is apt to ruin it for subsequent use. When the prepared paper strip is rolled, however, the exposed surface of Ithe adhesive will adhere slightly to the paper as it is rolled but will readily strip therefrom upon unrolling.

In use our prepared mask strip may be very readily and quickly applied by a single workman and will be firmly held in place against all movement or removal by a stripping force at right 5I angles to the surface. The paper is wide enough to afford ample protection of the surface adjacent that to which the color is to be applied. As soon as the need for the mask is passed the mask may be readily stripped from place and rerolled for use in a. subsequent operation. We have -found lthat when theadhesive is made in the manner lhereinbefore set "forth it will still be serviceable after many operations even though the striphas not been rolled and the adhesive has theretofore been left open to the atmosphere.

In course of time the edge of the stri-p along 'the outer edge of the adhesive isapt to becomeA somewhat uneven because of uneven accumula-z tion of the paint,-varnish or lacquer andY then unevenness is apt to occur long before the adhesive has reached a condition where it is no longer readily adhesable to surfaces to be protected. Consequently, while a comparatively narrow strip of adhesive is sufficient to successfully hold the paper against displacement, it is quite desirable that it be originally of sufficient width to permit occasional trimming so that a fresh sharp edge may be presented along the line up to which the desired color is to be applied. y

We claim:

1. 'Ihe method of manufacturing an adhesive tape which includes the steps of providing a ilexlble backing material, mixing together a composition containing a' rubber base material of a nature to be insoluble in the presenceof water or the conventionally solvent vehicles employed ln paints and varnishes, forminglthe same into a layer, pre-forming one surface thereof, moistening said layer composition on the opposite surface oil, all formed to a doughy consistency amenable to rolling into their lms.

3.The improved method of manufacturing an adhesive sheet which is normally pressure sensitive, which includes the steps of producing Ya rubber base adhesive material containing modifying agents to form ay tacky mass into a layer and rolling the same to predetermined thickness, then.

moistening one surface of the layer with, a solvent and applying same underpressure to a cellulosic backing material.

4. The improved method of manufacturing an adhesivesheet whichl is normally pressure sensitive which includes the stepsofproducing a rubber base adhesive material'containing modifying agents to form `atac'ky vmass .of doughyY consistency,` rolling-the sameto a predetermined thickness, and contacting one surface thereof to a re-.

movable strip, then moistening the oppositesurface of the layer with .a solvent and uniting a cellulosic backing materialto the surfaceso 'moistened under application of pressure.

JOHN OMER DOTY.

. PAUL C. ORCUTT. 

